Boiling to help gelatinize would be helpful. The starches in raw barley would be less accessible if they aren't gelatinized. Baking the malt doesn't gelatinize the starch. You have to have water in the kernel.
Be very careful with how much is added to the total grist. Flaked barley and raw barley have a distinctive taste in my opinion. It's relatively masked in a beer like a stout, but when you have a lighter flavored beer, the taste is notable and not desirable. In addition, the beta glucans that you add to the wort are very effective body producers. Even at very low concentrations. The problem with that is that when you pour a beer like that, the head is HUGE and doesn't fall very fast. For a commercial beer, that would be disaster. The bars would be unable to produce a good pour out of the tap.
You may ask, what about Guinness and its head? That beer is thinned by its low mash pH and the raw barley they add helps boost that back up to beyond a normal all malt body. However, the modest 'carbonation' provided by the nitrogen is very fine and not very effervescent. That allows a bartender to serve that beer in a reasonable amount of time. But, you may be aware that a proper Guinness pour demands a 2-step pour and some waiting. Big chewy body is not always a good thing.
While a stout might have 5 percent, I find that milder flavored beers need no more than about 1/2 percent to produce the intended body-building effect.
Enjoy!